1. Field of the Invention
The present invention relates to an electronic private branch exchange and more particularly to a tone sending device to inform a telephone or other line of a state of a call or a line.
2. Description of the Related Art
In a conventional electronic private branch exchange, a dial tone or a ring back tone to inform a state of a call or a line is sent to an extension telephone or a central office line by coding tone information converted to a PCM (Pulse Code Modulation) signal, storing it in a memory such as a ROM or a like, then reading tone PCM information from the memory in synchronization with a PCM period to produce a PCM code corresponding to a type of a tone to be used and by outputting the tone through a time sharing switch.
There are various methods for sending a holding tone using a desired tone derived from a tone source. One of the methods is to send out the holding tone by mounting a holding tone sending circuit within an electronic private branch exchange, an external voice inputting terminal and a changeover switch used to select either of a tone from the holding tone sending circuit or an external tone from the external voice inputting terminal and by transferring the selected tone as the holding tone to the extension telephone or the central office line to inform the state of the call or a line. Another method is to send out the holding tone derived from a holding tone sending device by connecting the holding tone sending device to a specified line of an interface circuit connected to a time sharing switch, by connecting the specified line through the time sharing switch to the interface circuit of the extension telephone being in an on-hold state or of the central office line, depending on an on-hold operation.
One example of a conventional digital tone generating circuit is disclosed in Japanese Patent Application Laid-open No. Hei6-086376. The disclosed digital tone generating circuit is chiefly composed of a memory circuit storing information obtained by encoding a tone signal (audible tone) converted to the PCM signal, an interval signal (continued audible tone) and an arranging tone signal (a combined signal of the tone signal and the interval signal), a SEL (selecting circuit) and a RAM circuit to designate arbitrary arranging information read from the memory circuit, and operating timing for all circuits is suitably controlled by a synchronization controlling circuit.
There is, however, a problem in the conventional tone generating circuit in that it is impossible to use an external voice message as a freely changeable tone. That is, in the conventional tone generating circuit, since a tone derived from a fixed tone source stored in the memory circuit such a ROM or a like is used, when a content of the fixed tone source is to be changed, change of the ROM itself storing the fixed tone source or use of another ROM is necessary and, in any case, the tone derived from the fixed tone source cannot be used as a freely changeable voice message.
Moreover, in the conventional tone generating circuit, there are other problems in that use of the voice message as a variety of tones to inform of the state of the call or the line, utilization of the external voice message in combination with the tone derived from the fixed tone source or selective use of either of the voice message from outside or the tone derived from the fixed tone source are impossible.
Also, in the conventional tone generating circuit designed to introduce the voice message from outside by using an exclusive interfacing device, many exclusive interfacing devices are required if two or more types of tones have to be treated.
Furthermore, in the conventional tone generating circuit not provided with such the,exclusive interfacing device, if the interfacing device is used simply as a port to introduce the external voice message, the time sharing switch that can be used to select either of the voice message or the tone derived from the fixed tone source depending on a type of the tone to be used is required.
In view of the above, it is an object of the present invention to provide a tone sending device of an electronic private branch exchange which is capable of sending out a tone informing an extension telephone or a central office line of a state of a call or a line without additional mounting of exclusive configurations or devices, or complicated processing, of using not only a predetermined tone derived from a preliminarily fixed tone source stored in a memory but also a voice message from outside and of selectively using either of the voice message or the tone derived from the tone source depending on a type of the tone to be used.
According to a first aspect of the present invention, there is provided a tone sending device of an electronic private branch exchange comprising:
a means using a voice message from outside as a tone to inform an extension telephone and/or a central office line of a state of a call or a line.
Also, according to a second aspect of the present invention, there is provided a tone sending device of an electronic private branch exchange comprising:
a first means introducing a voice message through an interface into a time sharing switch;
a second means setting a selection by a type of a tone so as to select either a predetermined tone from a preliminarily fixed tone source or the voice message; and
a third means controlling the time sharing switch so as to connect a slot designated by the type of the tone for transferring a tone corresponding to the state of the call or the line, with a slot designated by the type of the tone to which a tone is desired to be outputted;
whereby the tone sending device sends selectively, selected by a type of a tone, out either the determined tone or the voice message as a variety of tones to be used to inform a telephone or other line of the state of the call or the line.
Furthermore, according to a third aspect of the present invention, there is provided a tone sending device of an electronic private branch exchange comprising:
a voice message generator for generating a voice message and outputting it as a first PCM (Pulse Code Modulation) signal;
a fixed tone generator for outputting several types of fixed tones as a second PCM signal in a predetermined order;
a switching device for receiving the voice message and outputting it to a selecting circuit, receiving a signal from the selecting circuit and outputting it to a telephone or other line;
a selecting signal generating circuit for storing tone selecting information corresponding to a type of a tone and for generating, in accordance with the tone selecting information, a selecting signal for the selecting circuit;
whereby the selecting circuit operates to receive a third PCM signal, through its one input terminal, in a state in which outputting order of each of the tones to be outputted as the first PCM signal and outputting timing of the first PCM signal conforms to the outputting order of each of the tones to be outputted as the second PCM signal and outputting timing of the second PCM signal and to receive the second PCM signal fed by the fixed tone generator through its other input terminal, and further the selecting circuit operates to select either of the second and third PCM signals depending on the type of tones to be used for informing a state of a call or a line in accordance with the selecting signal and to output a selected signal as a fourth PCM signal to the switching signal.
In the foregoing, a preferable mode is one wherein the voice message is a changeable voice message.
Also, a preferable mode is one that wherein further comprising an interface interposed between the voice message generator and the switching device, through which the voice message is introduced. Also, a preferable mode is one wherein the switching device is a time sharing switch.
Also, a preferable mode is one wherein a controller operates to output selecting information to the selecting signal generating circuit depending on the type of the tone to be used for informing the state of the call or the line and to cause the voice message inputted as the PCM signal from the interface to be subject to outputting order of types of tones outputted from the fixed tone generator and outputting timing of each of the PCM signals; and further operates to instruct the switching device to connect a slot for transferring the tone, to inform of a state showing that dialing is in progress or a telephone call is in progress during processing of calls, outputted as the PCM signal from the selecting circuit, with a slot of an interface of an extension telephone or a central office line.